The consumption of sugar-sweetened beverages (SSB) has increased steadily over the past decades, resulting in the dramatic increase of fructose intake as it is one of the main ingredients of artificial sweeteners. Recently, large epidemiological studies have documented the association between a high-fructose-diet and hepatic steatosis, and other metabolic disorders. So it is interesting for scientists to explore the underlying mechanism. This study aims to investigate the effect of dietary fructose and gut microbiota and the hepatosteatosis in healthy men. Serum and fecal metabolomics will be investigated.

This is a single center, randomized, controlled study. 60 healthy men will be recruited according to the inclusion criteria. All subjects are randomly allocated to Group A and Group B, who orally takes 75g and 150g fructose daily respectively. Subjects in Group A will be instructed to drink fructose solution containing 75g fructose per day, and those in Group B will be instructed to drink fructose solution containing 150g fructose per day. The intervention will last four weeks. The anthropomentric data will be collect with questionnaire and serum and fecal samples collected at baseline and the end of the intervention. The effect and mutual interaction of dietary fructose and microbiota will be explored. The effect of dietary fructose on hepatosteatosis will be investigated as well.

Inclusion Criteria:

1. Healthy men aged from 18 to 40 (including both ends);
2. Body mass index (BMI) ranges from 18.5 to 23.9 kg/m2 (including both ends);
3. The body weight has not changed dramatically in the past 3 months (±3kg);

Exclusion Criteria:

1. Subjects who have received antibiotic-related treatment, proton pump inhibitor treatment, or glucocorticoid hormone treatment within 1 month before enrollment;
2. Subjects with diabetes or cardiovascular disease or other chronic diseases who require long-term medication;
3. Subjects who suffered from an acute gastrointestinal diseases within the past month, or who have an history of chronic gastrointestinal disease or hepatitis;
4. Subjects with a history of gastrointestinal surgery;
5. Subjects with abnormal liver or kidney function, or severe cardiovascular diseases;
6. Subjects with mental disorders or impaired cognitive function;
7. Poor compliance;
8. Participates enrolled in other clinical research at the same time;
9. Other unsuitable occasions judged by clinicians..